Refuse vehicles are typically used by municipalities and waste-removal contractors to collect refuse material from widely dispersed sources such as residences or commercial establishments and to transport the collected refuse to a central dump site such as a landfill, recycling center, or transfer point where it can be ejected. Since the dump site may be located a long distance from the collection area, it is desirable to "pack" (i.e, compress or compact), the refuse material as it is collected so as to maximize the number of sources which can be serviced by a vehicle of a given storage capacity before another trip to the dump site is necessary. A refuse vehicle typically comprises a conventional truck chassis or trailer chassis upon which is mounted a refuse body having apparatus for collection, packing, storage, and ejection of the refuse.
Three general classes of refuse vehicles are commonly encountered. A "rear-loader" type refuse vehicle is typically provided with a hopper, i.e., receiving compartment, which is accessible from the rear of the vehicle and a movable blade for packing the refuse forward from the hopper into a storage area for storage. A "front-loader" type vehicle is typically provided with a hopper which is accessible from the top, a power-actuated loading mechanism for elevating and dumping refuse containers from the front of the vehicle into the hopper, and a movable blade for packing the refuse rearward from the hopper into a storage area for storage. A "side-loader" type vehicle is typically provided with a hopper which is accessible from the side. Some side-loaders have a power-actuated loading mechanism adapted for gripping, elevating and dumping refuse containers from the side of the vehicle into the hopper, however, other side-loaders utilize manual feeding of the hopper. A movable blade is also provided for packing the refuse rearward from the hopper into a storage area for storage.
It is generally desirable to maximize the number of sources served by a refuse vehicle during a given time period. In many situations the vehicle's crew can access refuse containers for loading into the hopper faster that the packing blade can complete its packing cycle, i.e., extending the packing blade to pack material from the hopper into the storage compartment, then retracting the packing blade to its original position. Many refuse body designs, however, cannot accommodate loading of the hopper until the packing blade has finished its packing cycle since refuse material may otherwise fall behind the extended blade and jam the mechanism. In these cases, the crew must wait for the packing blade to complete its cycle before loading the hopper, thus increasing the time required for the crew to complete their route. A need therefore exists, for a refuse body apparatus which allows dumping of refuse material into the loading compartment at any time during the packing operation.
After the storage area of the refuse body has been filled with packed refuse material, the material must be transported to the dump site and ejected. In some vehicles, this ejection is accomplished by opening a rear door on the body and tilting the entire body at an angle so that the packed "bale" of refuse slides out of the opened rear door. However, tilting the refuse body during the ejection operation raises the center of gravity of the entire vehicle, making it more susceptible to overturning, a very dangerous condition. This danger is especially high when the ejecting operation takes place at a dump site having soft or non-level ground, such as a landfill. A need therefore exists, for a refuse body apparatus having full ejection of refuse without tilting of the body.
In other vehicles, ejection of the packed refuse bale is accomplished by opening a rear door and extending an ejecting blade from the front of the storage compartment to the rear doorway, thereby pushing the refuse bale out the opened rear door without tipping the body. This is termed "full ejection." While this full ejection method avoids the dangers inherent in the tipping of the body, it typically requires an ejecting blade actuator which can extend the entire length of the storage compartment. Refuse bodies having full ejection, especially front-loader and side-loader type bodies having long storage areas, typically utilize one or more multi-stage hydraulic cylinders (i.e., units well known in the art comprising a barrel, one or more telescoping, fluid actuated sleeves and a telescoping, fluid actuated plunger which allows the extended unit to "telescope" to several times its retracted length) to achieve the required length of movement required. Although these multi-stage cylinders may provide a compact actuator unit with long extension length, they are generally significantly more expensive to purchase initially, significantly more expensive and complicated to maintain, and generally have a significantly shorter life than single-stage cylinders (i.e., units having only a single movable fluid actuated rod) used under the same conditions.
In some refuse bodies using full ejection to eject the packed bale, especially front-loader and side-loader type bodies having long storage areas, the same multi-stage hydraulic cylinders used for the ejecting operation are also used for the refuse packing operation. In such cases, the multi-stage cylinders are partially extended (i.e., extended only a portion of their full length) to perform the packing operation and are fully extended only to perform the ejecting operation. Such a design thus requires only one type of actuator to accomplish two functions. However, these designs subject the multi-stage cylinders to relatively high-frequency use since the packing operation is typically performed hundreds of times per day while the ejecting operation is typically performed only several times per day. Although the multi-stage cylinder is only partially extended most of the time, this nonetheless results in increased wear on the multi-stage cylinders and increases the need for expensive and time-consuming maintenance on them.
In rear-loader type bodies, single-stage cylinders are generally used for the packing operation (which packs from the rear) and multi-stage cylinders are generally used for the full eject operation (which ejects from the front). It is known from experience with these rear-loader type bodies that using only the single-stage cylinders for the relatively frequent packing operation and using the multi-stage cylinders only for the relatively infrequent full ejection operation results in long life and reduced maintenance on the expensive multi-stage cylinders. A need therefore exists, for an apparatus for use in front-loader and side-loader type refuse bodies in which both packing and ejecting are accomplished from the front of the storage area which utilizes only single-stage hydraulic cylinders for the packing operation.